How a false claim about Iran executions spread online

In recent days, social media posts providing alarming updates on protesters in Iran have been shared by tens of thousands online.

The posts, including by prominent officials and celebrities, falsely claimed that Iran's parliament had voted to execute thousands of detained protesters.

Iran's parliament does not issue sentences; that's a power that rests with its judiciary branch. So how did this inaccurate claim originate?

Protests in Iran erupted over the death of 22-year-old Mahsa Amini, who died on Sept. 16 after being taken into custody by the "morality police" in Tehran for allegedly wearing her hijab improperly.

The nationwide protests in the weeks since have been violently suppressed by the government, as Iranians demand a change in regime. Internet blackouts and government crackdowns have made it difficult for reliable information to circulate within Iran and abroad.

"We try to see everything by our own eyes because that's the most true thing that we can have the access to," a protester, who is not being identified to protect her safety, told ABC News from Iran. "The Internet is so weak, so we cannot have the access easily."

On Nov. 6, 227 out of 290 members of Iran's parliament signed a letter urging the judiciary to impose harsher, quicker sentences on protesters, as reported by the state-controlled IRNA News Agency. The lawmakers asked for severe punishment of those who incited riots, calling them "mohareb" -- which in Sharia law means "enemy of God." Some could face capital punishment if convicted.

In the days following the statement, some outlets incorrectly reported the developments, including Newsweek, which on Nov. 8 published an article with the misleading headline: "Iran Votes to Execute Protesters, Says Rebels Need 'Hard Lesson.'"

The article linked to a tweet by a Ukrainian news source that claimed Iran's parliament voted to execute protesters.

Newsweek ultimately issued a correction a week later on Nov. 15: "This article and headline were updated to remove the reference to the Iranian Parliament voting for death sentences. A majority of the parliament supported a letter to the judiciary calling for harsh punishments of protesters, which could include the death penalty."

But by that point, the article and other versions of the false claims had already been shared widely on social media, including by prominent accounts and celebrities who appear to have been unaware of the inaccuracies. Among them were Viola Davis and Canadian Prime Minister Justin Trudeau.

"How this isn't getting more coverage right now is beyond me, but that needs to change now!" a since-deleted post on Davis' Facebook account stated.

"So the thing about misinformation -- it's not new, we've always had rumors and gossip. But we've never had a mechanism that meant that it could travel around the globe in seconds," Brown University professor Claire Wardle, a misinformation expert, told ABC News. "And that happens even more quickly when you have celebrities and politicians with huge followings who become these kind of superspreaders."

The spread of misinformation by people who may be turned to for trusted information "also complicated the situation," she added.

One commonly shared infographic featured a close-up of a woman's face drawn with red lines, seemingly meant to look like tears of blood, accompanied by block text that stated the misinformation about death sentences for thousands of protesters.

"All of this plays into a piece of content that ticks all the boxes," Wardle said.

Many of the posts were deleted, while those still up were eventually flagged as false by Instagram and Facebook, limiting their circulation. Twitter did not as quickly label it as false and overall, ABC News calculated that the falsehood was shared more than 66,000 times on Twitter alone.

"All of [this] sharing ... has not helped a really complex situation in Iran and it hasn't helped Iranians," Wardle said. "And so that's what we have to recognize, the harm that this kind of sharing causes."

While reports of mass executions are not true, five people are currently facing the death penalty in cases linked to the ongoing protests, according to the Iranian judiciary. At least nine others have been charged with offenses that carry a potential death sentence.

Meanwhile, Iranian authorities have deployed violent tactics to try to quell the demonstrations. Civil society organizations monitoring the situation have reported to the United Nations Human Rights Office that at least 300 people have been killed by the excessive use of force by security forces, including more than 40 children.

The number of protesters detained and ultimately charged is unclear. One group, the Human Rights Activists in Iran, estimates that more than 16,000 people have been detained since the start of the protests. The UN has determined that more than 2,400 people have been indicted as of Nov. 13, based on reports from state media and local officials.

For Wardle, it's important to recognize that those inadvertently sharing the misinformation were "wanting to do good" and raise awareness, as opposed to profit off the situation or create harm.

"But it's a reminder that even when we want to do good, we have to stop and think because there has been harm caused by this," she said.

"We are now living in an age where our attention span is so short that the image and the headline will do. And that's why these kinds of problems emerge," she added.

ABC News' Desiree Adib contributed to this report.